When Mayor Michael R. Bloomberg and Governor David Paterson joined developer Jerry Speyer at a March 26 press conference announcing Tishman Speyer’s $1 billion-plus bid to lease the Hudson Yards from the MTA, everyone gathered around the Plexi-enclosed model and smiled for the cameras. The model depicts nine towers, many with porches over the High Line, and a public forum with a big staircase. But this diorama, a masterplan by Murphy/Jahn and Peter Walker and Partners, is simply a placeholder: the western half of the railyards has to go through a rezoning that will shape building heights and masses, all of this after Tishman invests $2 billion to build a platform over the yard and get office construction underway. When complete in 2016, the design will be as different from the model as the politicians surrounding it.

This deal doesn’t focus on architecture: it’s about getting money to the MTA. The agency is facing serious deficits, and Tishman’s willingness to sink capital into the neighborhood was particularly attractive. “Cash flows one way,” explained MTA’s Gary Dellaverson to his board before unanimous approval for the tentative deal. “Tishman’s obligation is to us.” The developer outlasted an early dropout (Brookfield Properties), a bidder for half of the site (the Related Companies), and a near-match from the Durst Organization and Vornado Realty Trust that Dellaverson described to his board as slightly less and later than Tishman’s. Tishman is working out terms to lease the 26-acre site for 99 years, with rights to develop the western half one parcel at a time, selling each parcel only after paying the MTA for it and paying hundreds of millions in cash if it decides to quit.

But what will the new neighborhood look like? The draft commitment letter obliges the developer only to produce a place “consistent with developer site plan and master plan proposal.” Tishman will probably sell any parcel the 7 subway extension and economy make valuable when it’s complete. At the ceremony, CEO Jerry Speyer affirmed that “any architect” could design the school, apartment towers, office buildings, cultural center, or park within the guidelines of the masterplan. Speyer’s son Rob, the company’s president, insisted the builders would “keep an open mind” about whether the High Line stays intact, and on other questions that preoccupy urban-design types.

So the office towers’ cantilever over the High Line, the classical fountain in the center, and the multicolored rooftops could vanish. Jerry Speyer said his group remains “absolutely” set on building the staircase from 10th Avenue, which is part of the master plan and which Rob Speyer has eagerly described as Manhattan’s next great public space. But a challenge in making a public space great will be getting people there: The site slopes downwards and will be hard to reach unless the planned 7 subway line extension finds money for a stop at 10th Avenue. “The most challenging part is how to avoid an overly-programmed, sterile, and disconnected end result, “ said FXFowle partner Dan Kaplan, who worked on Durst/Vornado’s bid and the Hudson Yards Development Corporation’s design guidelines. Activists will undoubtedly also push for more affordable housing than the 391 units currently in the proposal.

At the ceremony, Governor Paterson said the best plan will come when “the elected community, developers, and planners consult with the public.” He was gently pointing out that the Uniform Land Use Review Procedure, a six-month gauntlet of community meetings and scoping documents, will determine how quickly Tishman can leverage its investment and how hard it can push for office space to recoup extra spending.